In a radical departure from the traditional design, a Caltech group has produced a flexible solar cell using an array of silicon wires. By packing light-scattering particles in among the wires, the researchers have achieved efficiencies up to 85%, despite the fact that the silicon wires take up only 2% of the volume, with significant cost reduction expected in a commercial version. To learn more, see this Caltech press release and this Scientific American article.